Python C api - 函数重载

我有许多接受不同参数的 C 函数，例如

foo_i(int a)

foo_c(char c)

是否可以在 python C api 中重载这些函数？

我尝试使用以下方法表：

static PyMethodDef test_methods[] = {
    {"foo", (PyCFunction)foo_i, METH_VARARGS, "int"},
    {"foo", (PyCFunction)foo_c, METH_VARARGS, "char"},
    {NULL, NULL, 0, NULL}
};

但是当我调用foo从Python我总是最终使用表底部的函数。

关于如何调用两者的任何想法foo_i() and foo_c() using foo()在 python C-api 中？

Thanks!

要么给它们不同的 Python 级别名称，要么编写一个包装函数，对提供的参数进行类型检查并分派到正确的“真实”函数。 Python 本身不直接支持基于参数类型的重载函数。

如果您想要为您编写的包装，您可以看看pybind11，它确实允许您尝试的意义上的重载（它通过引擎盖下的类型检查包装器来实现，所以它只是语法糖，而不是行为的改变）。

未经测试的示例代码：

static PyObject*
foo_wrapper(PyObject *self, PyObject *arg)
{
    Py_buffer view;
    Py_ssize_t ival;

    // Check for/handle length 1 bytes-like object (bytes, bytearray, small mmap, etc.)
    if (PyObject_GetBuffer(arg, &view, PyBUF_SIMPLE) == 0) {
        if (view.len != 1) {
             PyErr_Format(PyExc_ValueError, "Must receive exactly one byte, got %zd", view.len);
             PyBuffer_Release(&view);
             return NULL;
        }
        foo_c(((char*)view.buf)[0]);
        Py_RETURN_NONE; // Or convert return from foo_c if it exists
    }

    // Check for/handle integer-like object that fits in C int
    PyErr_Clear(); // Ignore error for objects not supporting buffer protocol
    ival = PyNumber_AsSsize_t(arg, PyExc_ValueError);
    if (PyErr_Occurred()) {
        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
            // Replace with general error message about both accepted argument types,
            // since only reporting error from int conversion might confuse folks
            PyErr_Format(PyExc_TypeError, "Argument must be length 1 bytes-like object or integer; received %R", Py_TYPE(arg));
        }
        return NULL;
    }

    // Check valid range (Py_ssize_t often larger than int)
    if (ival < INT_MIN or ival > INT_MAX) {
        return PyErr_Format(PyExc_ValueError, "Integer must be in range [%d-%d]; received %zd", INT_MIN, INT_MAX, ival);
    }

    foo_i((int)ival);
    Py_RETURN_NONE; // Or convert return from foo_i if it exists
}

static PyMethodDef test_methods[] = {
    {"foo", (PyCFunction)foo_wrapper, METH_O, "Wrapper for foo_c and foo_i"},
    {NULL, NULL, 0, NULL}
};